i agree...keeping track of ppms is crucial weather its ppms of the water you are starting with or ppms of your nutes/water mix (if you are using artificial nutes). Keeping track enables you to tune your feeding way closer to your limits. I've grown with dyna grow in soil and hydro and general...
i would top her...i can relate to your anxiety about cutting your plant as i recently took clones from a mother plant for the first time but my plant did seem to suffer any ill effects at all. have you considered fiming? what are your space restrictions?
just outa curiosity what was the determining factor in you choice in leds...i was checkin out the isis leds (probly gonna get some myself) and see that there are 2 different types...the isis-1,2,or3 and the fx series (more light wavelengths)